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Q: Engine over-heating and Radiator then overflows fluid or steam.

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We have by-passed the usual route for powering the cooling fan. We are using a switch placed on top of the front fender from the car battery to power the cooling fan "by hand". It seems the engine overheats very quickly, maybe at about 4 miles & definitely by a 10 mile trip on the road, & when it does the radiator starts spilling over with fluid or steaming. You can hear the fluid inside the radiator boiling. We replenish the radiator fluid after one of these leaks & keep driving until it overheats again. I had a simple test done that indicates the head gaskets are still good. The Engine & transmission seem strong, so we don't want to ruin the engine. Someone said he thought there was a leak at the top of the radiator, told me that if we keep over-heating the engine, it will weaken the engine. IS that true? WE need this vehicle for short hauling trips almost every day!. What should we do to fix this that hopefully isn't going to cost more than the van or a newer one?

My car has 182000 miles.
My car has an automatic transmission.

A: First of all, overheating the engine will d...

First of all, overheating the engine will damage it. The list of reasons why is long, but here is a partial list of reasons why overheating the engine will ruin it.

  • The engine oil becomes much thinner at higher temps.
  • The engine oil can bake on to metal parts
  • Engines have very tight spaces for pressurized oil to lubricate the parts. When the engine is too hot, these spaces become smaller, or disappear all together.
  • Gaskets fail easier.
  • Metal parts can become warped.
  • You can overheat the transmission by overheating the engine. First of all they are bolted together and share the heat. Second, the cooler lines from the transmission go to the radiator to be cooled. When the radiator is boiling, this cooks the transmission fluid. Too much heat is the number one problem with transmission failure.

Second, there really isn't such a thing as weakening it, it's either runs well, or it doesn't. Considering that the engine is over heating in such a short time and distance, I would assume that the coolant is not circulating. The first and easiest part to check or replace would be the thermostat (as needed). While the engine is running and full of coolant, feel the upper and lower radiator hoses. If one is hot, and the other is not, the thermostat might be stuck closed.

Finally, I believe, based on my gut feeling, that the the water pump has failed. I have seen the impeller that circulates the coolant come off before. When this happens, the coolant does not circulate. It will heat up quickly when it can not reach the radiator. It will then boil. This does not happen at 212 degrees. A 50/50 mix of coolant and water, under 16 psi of pressure, will boil around 260 degrees. This creates extra pressure in the system. The radiator cap is designed to release any pressure over it's rating into the coolant reservoir. It will quickly overflow under these circumstances. The cooling fan that you hard wired will not do much of anything because the hot coolant in the engine never gets to the radiator, until its too late and boiling. You can confirm this when the engine is hot, the fan will be blowing cold air.

I would not delay having this repaired. Consider having a certified mechanic, such as one from YourMechanic, come by and address your overheating concerns.

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